The broad goals of this research project are to identify patterns of driving performance and safety errors resulting from age-related impairments in the useful field of view (UFOV), and to develop in-vehicle countermeasures that decrease crash risk and increase safety and mobility. The specific aims are to 1) determine optimal signal parameters for a driver alerting and collision warning device, 2) test the efficacy of the device in improving driver reactions in challenging situations in a high- fidelity driving simulator and on-road in an instrumented vehicle (IV); 3) characterize on-road driving performance, and search behavior and compensatory strategies, in at-risk drivers with UFOV impairments and comparison subjects operating an IV; 4) assess the effects of the safety intervention in at-risk drivers and comparison subjects on the road in the IV; and 5) estimate the benefits of the proposed safety interventions across the U.S. in terms of crashes averted. The research addresses these aims by testing 150 drivers ages 65 to 85 years, including 75 drivers with UFOV impairment and 75 comparison drivers without impairment. The groups will be randomized so than two-thirds receive the intervention and one-third act as controls. The experiments utilize ahigh-fidelity driving simulator, a state-of-the art instrumented vehicle, and sophisticated cognitive testing tools to systematically address driver impairments with in-vehicle solutions that improve a driver's ability to monitor information, allocate attention, and make accurate and timely decisions. The research team members are experts in human factors engineering, neurology, biostatistics, computer graphics, and cognitive science. As an outcome of these studies, we expect to (1) make recommendations on promising collision warning devices for at-risk drivers with UFOV loss, (2) develop basic information on real-world driving strategies in people at risk for collisions, (3) understand the efficacy of basic warning signal parameters and how they differ in cognitively impaired and normal drivers, (4) develop tools for possible clinical trials in drivers who have a variety of medical impairments. The results may be used to design safer automobiles that use new strategies and technologies for collision warning, perceptual augmentation, and attention management.